People who are not able to freely move around or get out of bed due to illness are usually confined to bed. A bedridden patient is prone to bedsores, which are local tissue necrosis caused by prolonged pressure on and insufficient blood flow to the skin and muscles that continuously contact with the bed. Almost all the bedridden patients are suffering from bedsores, which cause uncomfortable skin ulceration or even septicemia and amputation in worse conditions.
A common way to minimize the development of bedsores in a bedridden patient is to help the patient to change his or her lying position by, for example, rolling him or her over from one position to another periodically, such as every one or two hours, so as to avoid continuous pressure on the same body areas. The bedridden patients have become a heavy burden to nurses because a lot of time and energy is required to help the patients to change their lying position.
Therefore, air cushion beds are developed and introduced into the market for the purpose of preventing bedridden patients from forming bedsores. Generally, an air cushion bed internally includes a plurality of air bladders that can be alternately inflated and deflated. By inflating and deflating the air bladders alternately, it is possible to alternately and temporarily relieve different areas of the bedridden patient's body from prolonged pressure and accordingly reduce the possibility of developing bedsores. However, in the event the air bladders are insufficiently inflated, the air cushion bed is almost useless in terms of relieving the prolonged pressure on the bedridden patient's skin. On the other hand, in the event the air bladders are excessively inflated, the patient might undesirably slip down the air cushion bed.
It is therefore necessary to develop an air cushion bed that includes additional and better functions of determining whether there is a patient lying on the air cushion bed and whether the air bladders of the air cushion bed are properly inflated when a patient is lying thereon the bed.